1. Field of the Invention
This invention relates to a first detecting sheet and a first thermometric system for detecting and measuring the temperature of an object under test, and a heat treatment apparatus using these sheet and system for heat-treating semiconductor substrates, glass substrates for liquid crystal displays, glass substrates for photomasks, or substrates for optical disks (hereinafter simply called “substrates”), and particularly to a technique for detecting temperature by using crystal oscillators. This invention relates also to a second detecting sheet and a second thermometric system for detecting and measuring the temperature of a dummy substrate having thermometric elements with coils or antennas connected to crystal oscillators, and a heat treatment apparatus using these sheet and system for heat-treating substrates, and particularly to a technique for detecting temperature by using crystal oscillators.
2. Description of the Related Art
Conventionally, this type of apparatus includes a heat-treating plate for heat-treating a substrate placed thereon, a chamber vertically movable above the heat-treating plate, sensor coils arranged in the chamber for transmitting and receiving electromagnetic waves, and a measuring unit for measuring temperature based on frequencies received by the sensor coils. A dummy substrate has a plurality of thermometric elements arranged thereon. Each thermometric element includes a crystal oscillator having a natural frequency variable with temperature, and a coil connected to the crystal oscillator and capable of transmitting and receiving electromagnetic wave to/from the above sensor coils in noncontact fashion. When this dummy substrate is placed on the heat-treating plate, the sensor coils will receive from the coils the electromagnetic waves corresponding to the natural frequencies of the crystal oscillators. The measuring unit acquires a temperature of the dummy substrate based on the electromagnetic waves received. Since there is no need to extend wiring from the dummy substrate in order to connect it to the measuring unit, the chamber can be lowered completely to seal heat-treating space. Therefore, the temperature of a substrate at the time of heat treatment can be reproduced and measured with the dummy substrate (as disclosed in Japanese Unexamined Patent Publication No. 2004-140167, for example).
(I) The conventional apparatus noted above has the following drawback.
The conventional apparatus can measure only the temperature of the dummy substrate since the crystal oscillators are fixedly provided for the dummy substrate. Thus, the apparatus has a drawback of being unable to measure the temperature of an ordinary substrate undergoing heat treatment, for example.
(II) The conventional apparatus has the following further drawback.
In the conventional apparatus, the sensor coils provided in the chamber cannot be moved closer beyond a fixed distance to the coils attached to the dummy substrate. For example, even when the chamber is lowered, the distance between the sensor coils and the coils is about 10 mm. Therefore, with the dummy substrate having a plurality of coils arranged at short intervals, each sensor coil communicates not only with an opposed coil but also with adjoining coils. As a result, the temperature of the dummy substrate cannot be measured with sufficient accuracy. If the thermometric elements were arranged at enlarged intervals, the temperature of the dummy substrate could be measured accurately. However, this would provide fewer locations for temperature measurement, resulting in an inconvenience that a temperature distribution over the surface of the dummy substrate cannot be obtained properly.